Oilfield tubulars, such as pipes, drill strings, casing, tubing, etc., may be used to transport fluids or to produce water, oil, and/or gas from geologic formations through wellbores. In various stages of wellbore drilling and completion, such tubulars may be positioned within (i.e., “run-in”) the wellbore. During run-in, the oilfield tubulars may be maintained in a generally concentric position within the wellbore, such that an annulus is formed between the oilfield tubular and the wellbore (and/or another, surrounding tubular positioned in the wellbore).
Tools known as “centralizers” are employed to maintain this concentricity of the tubular in the wellbore. A variety of centralizers are used, including rigid centralizers, semi-rigid centralizers, and flexible, bow-spring centralizers. Bow-spring centralizers, in particular, are generally formed from two end collars and flexible ribs that extend between the collars. The ribs are expanded outward, and may be resilient, such that the bow-springs centralizers are capable of centralizing the tubular in the wellbore across a range of wellbore sizes.
Restrictions may exist in the wellbore in which the oilfield tubular is run. These restrictions may be areas where the inner diameter of the wellbore is reduced, which, in turn, reduce the clearance between the oilfield tubular and the wellbore. Examples of restrictions include lining hangers, the inner diameter of another, previously-run casing, and the wellhead inner diameter. When restrictions are present, bow-spring centralizers may be employed, and may be configured to collapse radially toward the oilfield tubular, allowing the centralizer to pass through the restrictions, while continuing to provide an annular standoff.
However, bow-spring centralizers generally have an operating envelope for clearance. When the clearance is too small, the bow-spring centralizers may be damaged when passing through the restriction, which may reduce the ability of the centralizers to provide a standoff below the restriction. Furthermore, oilfield tubulars generally include an amount of tolerance for the outer diameter (e.g., 1%), which can make determining the precise clearance size challenging.